Energy dependence of transverse particle production from SPS to RHIC

TL;DR

This study measures transverse momentum spectra in Pb+Pb collisions at 17.3 GeV, compares nuclear modification factors to RHIC results at 200 GeV, and investigates energy dependence of particle production and suppression patterns.

Contribution

It provides the first detailed comparison of nuclear modification factors at SPS and RHIC energies, revealing energy-dependent suppression effects in transverse particle production.

Findings

R_{AA} increases rapidly with transverse momentum

R_{CP} follows RHIC results except for pions at high p_T

K/pi ratios differ slightly from RHIC results

Abstract

Transverse momentum spectra up to 4.5 GeV/c were measured around midrapidity in Pb+Pb collisions at sqrt{s_{NN}}=17.3 GeV, for pi^{+/-}, p, pbar and K^{+/-}, by the NA49 experiment. The nuclear modification factors R_{AA}, R_{AA/pA} and R_{CP} were extracted and are compared to RHIC results at sqrt{s_{NN}}=200 GeV. The modification factor R_{AA} shows a rapid increase with transverse momentum in the covered region. The modification factors R_{AA/pA} and R_{CP} shows a saturation well below unity in the pi^{+/-} channel. The extracted R_{CP} values follow the 200 GeV RHIC results closely in the available transverse momentum range for all particle species, except for pi^{+/-}. For pi^{+/-} above 2.5 GeV/c transverse momentum, the measured suppression is smaller than that observed at RHIC. The K^{+}/pi^{+} and K^{-}/pi^{-} ratios were also extracted from the data and are compared to the 200 GeV RHIC results. The values of the former ratio is above, whereas the values of the latter ratio is slightly below the 200 GeV RHIC points.